Control methods for triatomines, Chagas disease vectors

FABIO GUIDOBALDI

Buenos Aires

Workshop; "Frontiers in Biosciences"; 2012

Sociedad Max Planck y el Ministerio de Ciencia, Tecnología e Innovación Productiva

"Control methods for triatomines, Chagas disease vectors" Fabio Guidobaldi Laboratorio de Neuroetología ecológica Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción, CICyTTP-CONICET. Materi y España, Diamante, Entre Ríos. Tel/Fax: 054-0343-4983086/87. CP 3105 fabioguidobaldi@cicyttp.org.ar Abstract Endemic Chagas disease in Latin America began as a neglected disease of poor, rural and forgotten human populations. The causal agent (the parasite Trypanosoma cruzi) is trasmitted among vertebrates by insects (vectors) mainly from the genera Triatoma, Panstrongylus and Rhodnius (Hemiptera; Reduviidae). The wild triatomines progressively adapted to the domestic environment, living in cracks in the mud walls and roofs of huts. Infested houses are usually sprayed in order to manage the population of insect, but is not ideal considering the effect of the insecticides over the people living there and the generation of resistant insects. We attempt to develop a method that is less aggressive for the environment, by understanding the ecology and neurophysiology of the insect response to different natural stimuli. We aim at developing lured trap devices to capture them. The lures can deliver a physical stimulus (heat, light, humidity), chemical stimulus (host odors, CO2, aggregation pheromone, etc), or a combination of two or more of those stimuli, thus generating a “multimodal bait” that ideally should result in a synergistic attractive effect between the components. At present we are developing a chemical bait. For this we carry out experiments with a trap olfactometer and locomotor compensator with two of the most important vectors, Triatoma infestans and Rhodnius prolixus).In the trap olfactometer we define activation as the total number of insects in the capture tubes (test + control) over the total of insects tested and attraction as the number of insects in the test capture tube over the total number of activated insects. Thus, this is a very challenging device in which the insects have to be activated, attracted and captured in order to obtain a response to an odor source. We are testing blends of synthetic odors that do not require the use of CO2, a compound that is either expensive or unpractical to use in the field. At present one of the synthetic blends that we are testing evokes a response  that is lower than positive controls but significantly higher than the negative control. Thus, the use of a synthetic host odor blend to develop a chemical lure for triatomines is a reachable aim. We are also studying the effect that host odors play in the oviposition behavior of triatomines. We found that host odors (mouse and chicken) significantly stimulate oviposition. However, the bugs prefer to oviposit at a distance from the host location. We propose that by interfering with the host odor detection by the bugs it would be possible to deter oviposition and slow the spread of the bugs. We plan to extend the list of single host odorants that are known to be detected by the bugs by using electrophysiological methods. This could render in an even more powerful attractant lure. Field tests are also planned, which will improve our knowledge about attractive blends, and allow a further improvement of the baits and trap device. Acknowledgements: We are greatfull to ANPCyT, CONICET and Fundación Bunge y Born.